Fouling during hemodialysis – influence of module design and membrane surface chemistry

Hemodialysis acts as an artificial kidney that selectively removes specific toxins, bio-compounds, or fluid from the main blood stream in a patient with kidney failure. The current process uses ultrafiltration-based membrane technology, where a semi-permeable material selectively extracts chemicals, such as uremic retention products, or remove excess water from blood by retaining certain compounds based on their size. As sugars, fats, proteins, biomolecules, cells, and platelets move into and across the tubular membrane in the hemodialysis process, the surface of the membrane begins to foul, which leads to major operational challenges that include sharp pressure drops with increasing operation times. The design of membranes with enhanced biocompatibility and anti-fouling properties is one avenue to increase the lifespan of the membrane used while facilitating the device operation and limiting the stress and discomfort of patients. This review presents interfacial interactions between blood components and membrane materials used in hemodialysis. The discussion analyzes the impacts of the hemodialyzer module design, membrane material morphology and surface chemistry on the long-term operation and performance of the hemodialyzers. Avenues for the development of next-generation-membrane-materials as well as new strategies to enhance the selective removal of toxic compounds from blood are also discussed.